Quantum process tomography of continuous-variable gates using coherent states

Fuente: arXiv
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Autori principali: Kervinen, Mikael, Ahmed, Shahnawaz, Kudra, Marina, Eriksson, Axel, Quijandría, Fernando, Kockum, Anton Frisk, Delsing, Per, Gasparinetti, Simone
Natura: Preprint
Pubblicazione: 2023
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author Kervinen, Mikael
Ahmed, Shahnawaz
Kudra, Marina
Eriksson, Axel
Quijandría, Fernando
Kockum, Anton Frisk
Delsing, Per
Gasparinetti, Simone
author_facet Kervinen, Mikael
Ahmed, Shahnawaz
Kudra, Marina
Eriksson, Axel
Quijandría, Fernando
Kockum, Anton Frisk
Delsing, Per
Gasparinetti, Simone
contents Encoding quantum information into superpositions of multiple Fock states of a harmonic oscillator can provide protection against errors, but it comes with the cost of requiring more complex quantum gates that need to address multiple Fock states simultaneously. Therefore, characterizing the quantum process fidelity of these gates also becomes more challenging. Here, we demonstrate the use of coherent-state quantum process tomography (csQPT) for a bosonic-mode superconducting circuit. CsQPT uses coherent states as input probes for the quantum process in order to completely characterize the quantum operation for an arbitrary input state. We show results for this method by characterizing a logical quantum gate constructed using displacement and SNAP operations on an encoded qubit. With csQPT, we are able to reconstruct the Kraus operators for the larger Hilbert space rather than being limited to the logical subspace. This allows for a more accurate determination of the different error mechanisms that lead to the gate infidelity.
format Preprint
id arxiv_https___arxiv_org_abs_2303_01451
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Quantum process tomography of continuous-variable gates using coherent states
Kervinen, Mikael
Ahmed, Shahnawaz
Kudra, Marina
Eriksson, Axel
Quijandría, Fernando
Kockum, Anton Frisk
Delsing, Per
Gasparinetti, Simone
Quantum Physics
Encoding quantum information into superpositions of multiple Fock states of a harmonic oscillator can provide protection against errors, but it comes with the cost of requiring more complex quantum gates that need to address multiple Fock states simultaneously. Therefore, characterizing the quantum process fidelity of these gates also becomes more challenging. Here, we demonstrate the use of coherent-state quantum process tomography (csQPT) for a bosonic-mode superconducting circuit. CsQPT uses coherent states as input probes for the quantum process in order to completely characterize the quantum operation for an arbitrary input state. We show results for this method by characterizing a logical quantum gate constructed using displacement and SNAP operations on an encoded qubit. With csQPT, we are able to reconstruct the Kraus operators for the larger Hilbert space rather than being limited to the logical subspace. This allows for a more accurate determination of the different error mechanisms that lead to the gate infidelity.
title Quantum process tomography of continuous-variable gates using coherent states
topic Quantum Physics
url https://arxiv.org/abs/2303.01451